Data retransmission method and apparatus to obtain information to be transmitted and to perform Polar encoding on the information

ABSTRACT

This disclosure provides a data retransmission method and apparatus. The method includes: A transmitting device obtains information to be transmitted for a tth time, where the information to be transmitted for the tth time includes Rt extension locations and information to be transmitted for a (t−1)th time, and the extension locations include Mt information bits and Lt check bits corresponding to the Mt information bits. The transmitting device then performs Polar encoding on the information to be transmitted for the tth time, to obtain a codeword after the Polar encoding, obtains a codeword for (t−1)th retransmission based on the codeword after the Polar encoding, and transmits the codeword for (t−1)th retransmission. A receiving device performs polar decoding after receiving the codeword for (t−1)th retransmission, to obtain a decoding result of codewords for t times of transmission. By performing, on an encoding side, check encoding on the information bits in an extension part, a decoding path can be reduced in a decoding process, thereby greatly reducing decoding complexity, and reducing storage overheads and calculation overheads.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/CN2018/107290, filed on Sep. 25, 2018, which claims priority toChinese Patent Application No. 201711065804.X, filed on Nov. 2, 2017.The disclosures of the aforementioned applications are herebyincorporated by reference in their entireties.

TECHNICAL FIELD

This disclosure relates to the wireless communications field, and inparticular, to a data retransmission method and apparatus.

BACKGROUND

At present, as a next generation wireless communications technology, afifth generation mobile communications technology (5G) has been widelyvalued and researched in the 3rd generation partnership project (3GPP)and various other international standardization organizations. Anapplication scenario of a 5G mobile communications system is as follows:for example, ultra-low latency and ultra-reliable communications (uRLLC)has higher requirements, such as high reliability and low latency. In acommunications system, channel encoding is usually used to improve datatransmission reliability and ensure communication quality, and a polarcode is the first channel encoding method that can be strictly proved to“reach” a channel capacity. The Polar code is a linear block code, agenerator matrix of the Polar code is G_(N), an encoding process of thePolar code is x₁ ^(N)=u₁ ^(N)G_(N), where u₁ ^(N)=(u₁, u₂, . . . ,u_(N)) is a binary row vector, and a length of the Polar code is N(namely, a code length). In addition, G_(N)=B_(N)F₂ ^(⊗(log) ² ^((N))),and

$F_{2} = \begin{bmatrix}1 & 0 \\1 & 1\end{bmatrix}$herein is an N×N transposed matrix, for example, a bit reversal ordertransposed matrix. It should be noted that B^(N) is an optional matrix,and may not be multiplied by B^(N) in some scenarios. F₂ ^(⊗(log) ²^((N))) is defined as a Kronecker product of log₂N matrices F₂. x₁ ^(N)is a bit after encoding (also referred to as a codeword), and the bitafter encoding is obtained by multiplying u₁ ^(N) and the generatormatrix G^(N) together. A multiplication process is an encoding process.In a polar encoding process, some bits in u₁ ^(N) are used to carryinformation, and are referred to as information bits, and a set ofindexes of the information bits is denoted as A. Some other bits in u₁^(N) are set to fixed values that are agreed on by a transmit end and areceive end in advance, and are referred to as frozen bits. A set ofindexes of the frozen bits is represented by a complementary set A^(c)of A. The frozen bits are usually set to 0. A sequence of the frozenbits may be randomly set provided that the transmit end and the receiveend agree in advance. A construction process of the Polar code is aselection process of the set A. This determines performance of the Polarcode.

In a communications application insensitive to a system delay, a hybridautomatic repeat request (HARQ) is a common transmission method used toimprove a system throughput. There are a plurality of Polar-code-basedHARQ manners, and a common Polar-code-based HARQ manner is anincremental redundancy (IR) HARQ. Specifically, in this IR HARQ manner,a transmitting device performs cyclic redundancy check (CRC) encoding onto-be-transmitted data during initial transmission, and encodes theto-be-transmitted data into a relatively short Polar code at acorresponding code rate. In each retransmission, extension is performedbased on Polar code lengths in previous transmission. Data of anunreliable information location during the initial transmission isplaced in an extension location. Polar encoding is performed on theextension location to generate an incremental redundancy bit, to obtainextension information after encoding, and the extension informationafter encoding is sent to a receiving device as retransmissioninformation. The receiving device combines the received retransmissioninformation with initially transmitted information and retransmittedinformation to form a long code for decoding.

However, in a currently used IR HARQ manner, as a quantity ofretransmission times increases, a code length of a combined long codealso increases continuously. If an existing CRC-aided successivecancellation list (CASCL) is used for decoding, there is a problem ofexcessively high storage overheads and relatively high decodingcomplexity.

SUMMARY

This disclosure provides a data retransmission method and apparatus, toresolve a problem of excessively high storage overheads and relativelyhigh decoding complexity as a quantity of retransmission timesincreases.

According to a first aspect, this disclosure provides a dataretransmission method. The method includes:

obtaining, by a transmitting device, information to be transmitted for at^(th) time, where the information to be transmitted for the t^(th) timeincludes R_(t) extension locations and information to be transmitted fora (t−1)^(th) time, and the extension locations include M_(t) informationbits and L_(t) check bits corresponding to the M_(t) information bits,where R_(t), M_(t), t, and L_(t) are integers greater than 0, t isgreater than 1, and M_(t) is less than R_(t);

performing, by the transmitting device, polar encoding on theinformation to be transmitted for the t^(th) time, to obtain a codewordafter the Polar encoding;

obtaining, by the transmitting device, a codeword for (t−1)^(th)retransmission based on the codeword after the Polar encoding; and

transmitting, by the transmitting device, the codeword for (t−1)^(th)retransmission.

In a possible design, before the obtaining, by a transmitting device,information to be transmitted for a t^(th) time, the method furtherincludes:

determining, by the transmitting device, that reliability of K_(t)information locations in the R extension locations is higher thanreliability of K_(t) information bits with lowest reliability in theinformation to be transmitted for the (t−1)^(th) time, where M_(t) isequal to K_(t)−L_(t).

In a possible design, M_(t) and L_(t) are positively correlated.

In a possible design, before the obtaining, by a transmitting device,information to be transmitted for a t^(th) time, the method furtherincludes:

determining, by the transmitting device, that the information to betransmitted for the t^(th) time meets a preset condition, where thepreset condition includes one or more of the following: a code length ofthe information to be transmitted for the t^(th) time belongs to a firstpreset range, a code rate of the information to be transmitted for thet^(th) time belongs to a second preset range, and a quantity of theinformation bits in the extension locations in the information to betransmitted for the t^(th) time belongs to a third preset range.

In a possible design, the obtaining, by the transmitting device, acodeword for a (t−1)^(th) retransmission based on the codeword after thePolar encoding includes:

performing, by the transmitting device, rate matching on the codewordafter the Polar encoding based on a preset code length and a preset ratematching manner, to obtain a to-be-retransmitted sequence after thematching, where the preset rate matching manner is one or more of thefollowing: puncturing rate matching, shortening rate matching, andrepetition rate matching; and

obtaining, by the transmitting device, the codeword for (t−1)^(th)retransmission based on the to-be-retransmitted sequence after thematching.

In a possible design, when the preset rate matching manner is thepuncturing rate matching, before the obtaining, by a transmittingdevice, information to be transmitted for a t^(th) time, the methodfurther includes:

determining, by the transmitting device, that the information to betransmitted for the t^(th) time meets a preset condition, where thepreset condition includes one or more of the following: a code length ofthe information to be transmitted for the t^(th) time belongs to a firstpreset range, a code rate of the information to be transmitted for thet^(th) time belongs to a second preset range, a quantity of theinformation bits in the extension locations in the information to betransmitted for the t^(th) time belongs to a third preset range, and aquantity of puncturing bits in the codeword after the Polar encodingbelongs to a fourth preset range.

According to a second aspect, this disclosure provides a dataretransmission method. The method includes:

receiving, by a receiving device, a codeword for (t−1)^(th)retransmission sent by a transmitting device, where the codeword for(t−1)^(th) retransmission is a retransmission codeword obtained by thetransmitting device based on a codeword after polar encoding that isobtained by information to be transmitted for a t^(th) time, theinformation to be transmitted for the t^(th) time includes R_(t)extension locations and information to be transmitted for a (t−1)^(th)time, and the extension locations include M_(t) information bits andL_(t) check bits corresponding to the M_(t) information bits, whereR_(t), M_(t), t, and L_(t) are integers greater than 0, t is greaterthan 1, and M_(t) is less than R_(t); and

performing, by the receiving device, Polar decoding on the codeword for(t−1)^(th) retransmission, to obtain a decoding result of codewords fort times of transmission.

In a possible design, the performing, by the receiving device, Polardecoding on the codeword for (t−1)^(th) retransmission, to obtain adecoding result of codewords fort times of transmission includes:

performing, by the receiving device, the Polar decoding on the codewordfor (t−1) times of transmission, to obtain a decoding result of thecodeword for (t−1)^(t) retransmission;

performing, by the receiving device, check decoding on the decodingresult of the codeword for (t−1)^(th) retransmission, to obtain a checkdecoding result; and

determining, by the receiving device, a reliable decoding path based onthe check decoding result, and decoding, based on the reliable decodingpath, codewords for first (t−1) times of transmission, to obtain thedecoding result of the codewords for t times of transmission.

In a possible design, the determining, by the receiving device, areliable decoding path based on the check decoding result, and decoding,based on the reliable decoding path, codewords for first (t−1) times oftransmission includes:

determining, by the receiving device, a decoding path with highestreliability based on the check decoding result, and deleting anotherdecoding path other than the decoding path with highest reliability; and

decoding, based on the decoding path with highest reliability, thetransmission codeword for the first (t−1)^(th) time.

In a possible design, the reliability of K_(t) information locations inthe R extension locations is higher than the reliability of K_(t)information locations with lowest reliability in the information to betransmitted for the (t−1)^(th) time, where M_(t) is equal toK_(t)−L_(t).

In a possible design, M_(t) and L_(t) are positively correlated.

In a possible design, the information to be transmitted for the t^(th)time meets a preset condition, where the preset condition includes oneor more of the following: a code length of the information to betransmitted for the t^(th) time belongs to a first preset range, a coderate of the information to be transmitted for the t^(th) time belongs toa second preset range, and a quantity of the information bits in theextension locations in the information to be transmitted for the t^(th)time belongs to a third preset range.

In a possible design, that the codeword for (t−1)^(th) retransmission isa retransmission codeword obtained by the transmitting device based on acodeword after Polar encoding that is obtained by information to betransmitted for a t^(th) time includes: the codeword for (t−1)^(th)retransmission is obtained based on a to-be-retransmitted sequence thatis after matching and that is obtained by a codeword on which ratematching is performed in a preset rate matching manner and that isobtained by performing Polar encoding on the information to betransmitted for the t^(th) time, where the preset rate matching manneris one or more of the following: puncturing rate matching, shorteningrate matching, and repetition rate matching.

In a possible design, when the preset rate matching manner is thepuncturing rate matching, the information to be transmitted for thet^(th) time meets a preset condition, and the preset condition includesone or more of the following: a code length of the information to betransmitted for the t^(th) time belongs to a first preset range, a coderate of the information to be transmitted for the t^(th) time belongs toa second preset range, a quantity of the information bits in theextension locations in the information to be transmitted for the t^(th)time belongs to a third preset range, and a quantity of puncturing bitsin the codeword after the Polar encoding belongs to a fourth presetrange.

According to a third aspect, this disclosure provides a dataretransmission apparatus. The apparatus includes a module or a means(means) configured to perform the method according to the first aspectand the implementations of the first aspect.

According to a fourth aspect, this disclosure provides a dataretransmission apparatus. The apparatus includes a module or a means(means) configured to perform the method according to the second aspectand the implementations of the first aspect.

According to a fifth aspect, this disclosure provides a dataretransmission apparatus. The apparatus includes a processor and amemory, where the memory is configured to store a program, and theprocessor invokes the program stored in the memory, to perform themethod according to the first aspect of this disclosure.

According to a sixth aspect, this disclosure provides a dataretransmission apparatus. The apparatus includes a processor and amemory, where the memory is configured to store a program, and theprocessor invokes the program stored in the memory, to perform themethod according to the second aspect of this disclosure.

According to a seventh aspect, this disclosure provides a dataretransmission apparatus. The apparatus includes at least one processingunit (or chip) configured to perform the method according to the firstaspect.

According to an eighth aspect, this disclosure provides a dataretransmission apparatus. The apparatus includes at least one processingunit (or chip) configured to perform the method according to the secondaspect.

According to a ninth aspect, this disclosure provides a computer storagemedium including a program, where the program is used to perform themethod according to the first aspect.

According to a tenth aspect, this disclosure provides a computer storagemedium including a program, where the program is used to perform themethod according to the second aspect.

In the data retransmission method and apparatus provided in thisdisclosure, the transmitting device obtains the information to betransmitted for the t^(th) time, where the information to be transmittedfor the t^(th) time includes R_(t) extension locations and theinformation to be transmitted for the (t−1)^(th) time, and the extensionlocations include M_(t) information bits and L_(t) check bitscorresponding to the M_(t) information bits. The transmitting devicethen performs Polar encoding on the information to be transmitted forthe t^(th) time, to obtain a codeword after the Polar encoding, obtainsa codeword for (t−1)^(th) retransmission based on the codeword after thePolar encoding, and transmits the codeword for (t−1)^(th)retransmission. A receiving device performs Polar decoding afterreceiving the codeword for (t−1)^(th) retransmission, to obtain adecoding result of codewords for t times of transmission. By performing,on an encoding side, check encoding on the information bits in anextension part, a decoding path can be reduced in a decoding process,thereby greatly reducing decoding complexity, and reducing storageoverheads and calculation overheads.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1(a) is a schematic architectural diagram of a communicationssystem according to the present disclosure.

FIG. 1(b) is a schematic architectural diagram of a communicationssystem according to the present disclosure.

FIG. 2 is a schematic flowchart of a data retransmission methodaccording to an embodiment of the present disclosure.

FIG. 3 is a schematic diagram of a decoding path according to anembodiment of the present disclosure.

FIG. 4 is a schematic structural diagram of information to betransmitted for a t^(th) time according to an embodiment of the presentdisclosure.

FIG. 5 is a schematic structural diagram of a data retransmissionapparatus according to an embodiment of the present disclosure.

FIG. 6 is a schematic structural diagram of a data retransmissionapparatus according to another embodiment of the present disclosure.

FIG. 7 is a schematic structural diagram of a data retransmissionapparatus according to still another embodiment of the presentdisclosure.

FIG. 8 is a schematic structural diagram of a data retransmissionapparatus according to still another embodiment of the presentdisclosure.

FIG. 9 is a schematic structural diagram of a data retransmissionapparatus according to still another embodiment of the presentdisclosure.

FIG. 10 is a schematic structural diagram of a data retransmissionapparatus according to still another embodiment of the presentdisclosure.

FIG. 11 is a schematic interaction diagram of a communications systemaccording to an embodiment of the present disclosure.

DESCRIPTION OF EMBODIMENTS

Embodiments of this disclosure may be applied to a wirelesscommunications system. It should be noted that the wirelesscommunications system mentioned in the embodiments of this applicationincludes but is not limited to: a narrowband internet of things system(NB-IoT), a global system for mobile communications (GSM), an enhanceddata rates for GSM evolution system (EDGE), a wideband code divisionmultiple access (WCDMA) system, a code division multiple access 2000(CDMA2000) system, a time division-synchronous code division multipleaccess (TD-SCDMA) system, a long term evolution (LTE) system, and threemajor application scenarios of a next generation 5G mobilecommunications system, namely, enhanced mobile broadband (eMBB), URLLC,and massive machine-type communications (mMTC).

In the embodiments of this disclosure, a terminal device (terminaldevice) includes but is not limited to a mobile station (MS, MobileStation), a mobile terminal (Mobile Terminal), a mobile telephone(Mobile Telephone), a handset (handset), a portable equipment (portableequipment), and the like. The terminal device may communicate with oneor more core networks by using a radio access network (RAN, Radio AccessNetwork). For example, the terminal device may be a mobile telephone (orreferred to as a “cellular” telephone), or a computer having acommunication function; or the terminal device may be a portable,pocket-sized, handheld, computer built-in, or in-vehicle mobileapparatus or device.

FIG. 1(a) and FIG. 1(b) are schematic architectural diagrams of acommunications system according to this disclosure.

As shown in FIG. 1(a), a communications system 01 includes a networkdevice 101 and a terminal 102. When the wireless communications network01 includes a core network, the network device 101 may be furtherconnected to the core network. The network device 101 may furthercommunicate with an internet protocol (Internet Protocol, IP) network200, for example, an internet (internet), a private IP network, oranother data network. A network device provides a service for a terminalwithin coverage of the network device. For example, referring to FIG.1(a), the network device 101 provides wireless access for one or moreterminals within coverage of the network device 101. In addition, theremay be an overlapping area between coverage of network devices, forexample, the network device 101 and a network device 201. The networkdevices may further communicate with each other. For example, thenetwork device 101 may communicate with the network device 201.

When the network device 101 or the terminal 102 transmits information ordata, a method described in the embodiments of this disclosure may beused. For ease of description, in the embodiments of this disclosure,the communications system 01 is simplified to a system that includes atransmitting device and a receiving device and that is shown in FIG.1(b). The transmitting device may be the network device 101, and thereceiving device is the terminal 102. Alternatively, the transmittingdevice is the terminal 102, and the receiving device is the networkdevice 101.

The network device 101 may be a device configured to communicate with aterminal. For example, the network device 101 may be a base transceiverstation (Base Transceiver Station, BTS) in a GSM system or a CDMAsystem, or may be a NodeB (NB) in a WCDMA system, or may be an evolvedNodeB (eNB or eNodeB) in an LTE system or a network-side device in afuture 5G network. Alternatively, the network device may be a relaystation, an access point, a vehicle-mounted device, or the like. In aterminal-to-terminal (D2D) communications system, the network device maybe a terminal that acts a function of a base station. The terminal mayinclude various handheld devices, vehicle-mounted devices, wearabledevices, or computing devices that have wireless communicationfunctions, or another processing device connected to a wireless modem,and user equipment (UE), a mobile station (mobile station, MS), and thelike in various forms.

The transmitting device is an encoding side, and may be configured toencode and output encoding information. The encoding information istransmitted to a decoding side on a channel. The receiving device is thedecoding side, and may be configured to: receive the encodinginformation sent by the transmitting device, and decode the encodinginformation.

FIG. 2 is a schematic flowchart of a data retransmission methodaccording to an embodiment of this disclosure. As shown in FIG. 2 , themethod includes the following blocks.

S201. A transmitting device obtains information to be transmitted for at^(th) time.

The information to be transmitted for the t^(th) time includes R_(t)extension locations and information to be transmitted for a (t−1)^(th)time.

These extension locations include M_(t) information bits and L_(t) checkbits corresponding to the M_(t) information bits. R_(t), M_(t), t, andL_(t) are integers greater than 0, t is greater than 1, and M_(t) isless than R_(t).

It should be noted that the information to be transmitted for the t^(th)time is prepared for (t−1) times of retransmission. Optionally, aftertransmitting initially transmitted information or retransmittedinformation, the transmitting device waits for the receiving device tofeed back an acknowledgment message. If the transmitting device receivesa success acknowledgment message (for example, an ACK message) within apreset time period, it is considered that the receiving devicesuccessfully receives the initial transmission information orretransmission information, and retransmission is not performed again.If a reception failure message (for example, a NACK message) is receivedwithin a preset time period, or no feedback is received after the presettime period, it is considered that information transmission fails, andretransmission is prepared. Alternatively, the transmitting deviceobtains the information to be transmitted for the t^(th) time after thepreset time period without considering feedback, prepares forretransmission, and so on. This is not limited in this disclosure.

During initial transmission, the transmitting device performs checkencoding on a to-be-transmitted information bit, generates a check bit,and forms a sequence of the check bit and the information bit; and thenperforms Polar encoding on the sequence, and transmits a codeword afterthe Polar encoding to the receiving device. Specifically, the checkencoding is performed on the K₁−L₁ information bits, to obtain the checkbit whose length is L₁, and form a sequence after the check encodingwhose length is K₁. A reliability order of subchannels (each subchannelcorresponds to one bit) is obtained based on a preset code length P₁ anda corresponding code rate K/P₁; and a subchannel sequence number set I₁corresponding to the sequence after the check encoding whose length isK_(t) (where a subchannel sequence number corresponding to the sequenceafter the check encoding whose length is K₁ used as an identifier of aninformation location), and a subchannel sequence number set F₁corresponding to a frozen bit (where a subchannel sequence numbercorresponding to the frozen bit is used as an identifier of a frozenlocation) are obtained. The sequence after the check encoding whoselength is K₁ mapped to the information location corresponding to I₁, thefrozen bit is mapped to the frozen location corresponding to F₁, andthen Polar encoding is performed on the whole for transmitting. P₁ is aninteger greater than 0.

Each time retransmission is to be performed, previously information tobe transmitted is extended based on a preset code length to form a newbit, and the new bit may be used to carry an information bit and afrozen bit that should be retransmitted. Optionally, the M_(t)information bits are selected and placed in the information location inthe extension locations.

In this disclosure, the check encoding is performed on the M_(t)information bits in the extension locations to obtain L_(t) check bits,and the L_(t) check bits are also placed in the extension locations.

It should be noted that the check encoding in this disclosure may beperformed in a plurality of manners (applicable to initial transmissionand retransmission), for example, cyclic redundancy check (CyclicRedundancy Check, CRC) encoding, parity check encoding, cyclic encoding,and Reed-Solomon (Reed-Solomon) encoding, Reed-Muller (Reed-Muller)encoding, Hamming encoding, and the like. These manners are not limitedin this disclosure, and are mainly used to assist a decoding side inreducing decoding complexity.

The M_(t) information bits, the L_(t) check bits, and the information tobe transmitted for the (t−1)^(th) time in the extension locations form along code, that is, form the information to be transmitted for thet^(th) time. A construction principle of the information to betransmitted for the (t−1)^(th) time is the same as a constructionprinciple of the information to be transmitted for the t^(th) time, anddetails are not described again.

S202. The transmitting device performs Polar encoding on the informationto be transmitted for the t^(th) time, to obtain a codeword after thePolar encoding.

S203. The transmitting device obtains a codeword for (t−1)^(th)retransmission based on the codeword after the Polar encoding.

The foregoing used Polar encoding is to encode the entire long codeincluding the M_(t) information bits, the L_(t) check bits, and theinformation to be transmitted for the (t−1)^(th) time. After thecodeword after the Polar encoding is obtained, a part of the codeword isextracted from the codeword and used as the codeword for (t−1)^(th)retransmission.

S204. The transmitting device transmits the codeword for (t−1)^(th)retransmission.

S205. The receiving device receives the codeword for the (t−1)^(th)retransmission sent by the transmitting device.

S206. The receiving device performs Polar decoding on the codeword for(t−1)^(th) retransmission, to obtain a decoding result of codewords fort times of transmission.

In this way, decoding can be completed, and information that thetransmitting device wants to transmit can be obtained.

In a specific implementation process, the performing, by the receivingdevice, Polar decoding on the codeword for (t−1)^(th) retransmission, toobtain a decoding result of codewords for t times of transmission mayinclude: performing, by the receiving device, the Polar decoding on thecodeword for (t−1)^(th) retransmission, to obtain a decoding result ofthe codeword for (t−1)^(th) retransmission; and performing checkdecoding on the decoding result of the codeword for (t−1)^(th)retransmission, to obtain a check decoding result, determining areliable decoding path based on the check decoding result, and decoding,based on the reliable decoding path, codewords for first (t−1) times oftransmission, to obtain the decoding result of the codewords for t timesof transmission.

Optionally, the receiving device may perform a Polar decoding operationby using CRC-aided successive cancellation list decoding (CA-SCL).

It should be noted that, after receiving the codeword for (t−1)^(th)retransmission, the receiving device combines the codeword for(t−1)^(th) retransmission and a received codeword for a first (t−1)^(th)time to form a long code, and transmits the entire long code to adecoder for decoding.

In a specific implementation process, due to different rate matching andthe like, when the codeword for (t−1)^(th) retransmission is combinedwith the received codeword for the first (t−1)^(th) time, crosscombination may be performed, that is, a part of the received codewordfor the first (t−1)^(th) time is inserted into the retransmittedcodeword. Therefore, in a process in which the receiving device performsthe Polar decoding (CA-SCL decoding) on the codeword for (t−1)^(th)retransmission, the receiving device also performs the Polar decoding onthe part of the received codeword for the first (t−1)^(th) time that isinserted into the retransmitted codeword, to obtain the decoding resultof the codeword for (t−1)^(th) retransmission.

When the transmitting device obtains the codeword for (t−1)^(th)retransmission, the transmitting device may extract a codeword of apreset length as the codeword for (t−1)^(th) retransmission.

It should be noted that, because the check encoding is also performed onthe information bits in the extension locations, before the Polarencoding is performed on the information to be transmitted for thet^(th) time, the check encoding is performed on all information bitscarried in each part. After obtaining the decoding result of thecodeword for (t−1)^(th) retransmission, the decoding side performs thecheck decoding, and may determine the reliable decoding path based onthe check decoding result.

In an optional manner, the transmitting device obtains the codeword for(t−1)^(th) retransmission based on the codeword after the Polar encodingother than the codewords for first (t−1) times of transmission. In thisway, the decoding side first obtains the decoding result of the codewordfor (t−1)^(th) retransmission by using the Polar decoding, so that theM_(t) information bits in the extension locations and the L_(t) checkbits corresponding to the M_(t) information bits can be obtained.Further, the check decoding is performed on the M_(t) information bitsand the L_(t) check bits corresponding to the M_(t) information bits, toobtain the check decoding result.

FIG. 3 is a schematic diagram of a decoding path according to anembodiment of this disclosure.

Specifically, there are N paths in a check process. A path with highestreliability is determined based on a check decoding result, and thenonly the path with highest reliability is reserved.

To be specific, a receiving device performs check decoding on a decodingresult of a codeword for (t−1)^(th) retransmission, then determines,based on the check decoding result, a decoding path with highestreliability, and deletes another decoding path other than the decodingpath with highest reliability, to further perform, based on the decodingpath with highest reliability, decoding on codewords for first (t−1)times of transmission.

As shown in FIG. 3 , after the check decoding is further performed onthe decoding result of the codeword for (t−1)^(th) retransmission, thedecoding path with highest reliability (a path 1-2-3-4 shown by anarrow) is determined based on the check decoding result, and thendecoding is further performed by using this path.

In a specific implementation process, the receiving device performsPolar decoding on a codeword received last time based on the decodingpath with highest reliability; further performs check decoding on aresult of the Polar decoding; and may further obtain the decoding pathwith highest reliability based on a check result, and reserve thedecoding path with highest reliability. The rest can be deduced byanalogy, until decoding of an initially transmitted codeword iscompleted. In this way, most reliable path decoding is used each time,thereby greatly reducing decoding complexity, and reducing storageoverheads and calculation overheads.

In this embodiment, a transmitting device obtains information to betransmitted for a t^(th) time, where the information to be transmittedfor the t^(th) time includes R_(t) extension locations and informationto be transmitted for a (t−1)^(th) time, and the extension locationsinclude M information bits and L_(t) check bits corresponding to theM_(t) information bits. The transmitting device then performs Polarencoding on the information to be transmitted for the t^(th) time, toobtain a codeword after the Polar encoding, obtains a codeword for(t−1)^(th) retransmission based on the codeword after the Polarencoding, and transmits the codeword for (t−1)^(th) retransmission. Thereceiving device performs Polar decoding after receiving the codewordfor (t−1)^(th) retransmission, to obtain a decoding result of codewordsfor t times of transmission. By performing, on an encoding side, checkencoding on the information bits in an extension part, a decoding pathcan be reduced in a decoding process, thereby greatly reducing decodingcomplexity, and reducing storage overheads and calculation overheads.

Optionally, the foregoing data retransmission method may be denoted as atransmission mode, and coexists with another transmission mode. Afterdetermining retransmission, the transmitting device selects atransmission mode for retransmission. Different transmission modes maybe applicable to different scenarios or conditions.

Before obtaining the information to be transmitted for the t^(th) time,the transmitting device determines that the information to betransmitted for the t^(th) time meets a preset condition. When thepreset condition is met, a transmission manner provided in thisembodiment of this disclosure is used. Specifically, the presetcondition includes one or more of the following: a code length of theinformation to be transmitted for the t^(th) time belongs to a firstpreset range, a code rate of the information to be transmitted for thet^(th) time belongs to a second preset range, and a quantity of theinformation bits in the extension locations in the information to betransmitted for the t^(th) time belongs to a third preset range.

The transmission manner provided in this disclosure may be denoted as a“first transmission mode”. Optionally, in some scenarios, in addition tothe transmission manner provided in this embodiment of this disclosure,the first transmission mode may further include an extended incrementalredundancy (IR) HARQ mode. In this extended IR HARQ mode, when thetransmitting device performs retransmission, the information to betransmitted for the t^(th) time further includes the extensionlocations, but the check encoding is not performed on the informationbits in the extension locations, that is, there is no check bit, andL_(t) is equal to 0. Further, the Polar encoding is performed on theinformation to be transmitted for the t^(th) time, to obtain thecodeword after the Polar encoding, and the codeword for (t−1)^(th)retransmission is obtained and sent to the receiving device. Thetransmission manner or the extended IR HARQ mode provided in thisembodiment of this disclosure may be determined based on differentparameters such as the first preset range, the second preset range, andthe third preset range.

The foregoing first transmission mode is selected when the presetcondition is met.

Optionally, another transmission mode may alternatively include a ChaseCombining (Chase Combining, CC) HARQ mode and an incremental redundancy(IR) HARQ mode. The transmission mode provided in this disclosure isdenoted as the first transmission mode (a name is not limited). In theCC HARQ mode, the transmitting device transmits a same coded signal eachtime the transmitting device performs retransmission. The receivingdevice directly adds log-likelihood ratios (LLR) of all receivedsignals, and then performs decoding. In the IR HARQ mode, thetransmitting device does not introduce a new information location, butextends a code length and a kernel based on the information to betransmitted for the (t−1)^(th) time. The extension locations carry afrozen bit, and a retransmitted codeword is transmitted after the Polarencoding. The IR HARQ mode is equivalent to retransmitting previouslytransmitted puncturing bits and some transmitted bits duringretransmission.

Specifically, Thredhold_1 is a code rate threshold, Threshold_2 is acode length threshold, and Threshold_3 is a threshold of a quantity ofthe information bits. Optionally, Thredhold_1=⅛; Threshold_2=1024, 2048,or 4096; and Threshold_3=5. This is not limited and is determined basedon a specific scenario.

When a long code (the information to be transmitted for the t^(th) time)constructed during retransmission exceeds a limit of a system code rateand a code length, the CC HARQ mode is selected. For example, as aquantity of retransmission times increases, an overall code rate of asystem is less than Thredhold_1 or a code length of the information tobe transmitted for the t^(th) time is greater than Threshold_2. In thiscase, the system does not support the code length or code constructionat the code rate, and cannot perform the first transmission mode.Therefore, the CC HARQ mode is selected.

When the quantity of the information bits in the extension locations isrelatively small, the IR HARQ mode is selected. For example, when thequantity of information bits in the extension locations is smaller thanThreshold_3 during retransmission, performance gain brought byintroducing the information bits is less than or equal to performanceloss brought by performing the check encoding on the new informationbits. Therefore, in this case, it is selected not to introduce theinformation bits, instead, the code length and the kernel are extendedbased on the information to be transmitted for the (t−1)^(th) time, andthen extended bits are transmitted, that is, the IR HARQ mode is usedfor transmission.

It can be learned that the first preset range is greater than or equalto Threshold_1, the second preset range is less than or equal toThreshold_2, and the third preset range is greater than or equal toThreshold_3.

Herein, the foregoing preset condition is not limited, and conditionsfor selecting the modes may be determined based on different scenariorequirements. This is not limited to the foregoing several modes, andanother transmission mode may alternatively coexist.

Based on the foregoing embodiment, the transmitting device furtherperforms rate matching after performing the Polar encoding.

Optionally, the obtaining, by the foregoing transmitting device obtainsa codeword for t^(th) retransmission based on the codeword after thePolar encoding may include: performing, by the transmitting device basedon a preset code length and a preset rate matching manner, rate matchingon the codeword after the Polar encoding, to obtain a retransmissionsequence after the matching. The transmitting device obtains thecodeword for (t−1)^(th) retransmission based on the retransmissionsequence after the matching.

The preset rate matching manner is one or more of the following:puncturing rate matching, shortening rate matching, and repetition ratematching.

It should be noted that the preset code length is a code length of theinformation to be transmitted for the t^(th) time. The code length ofthe information to be transmitted for the t^(th) time may bepreconfigured, and a rate matching manner is selected based on thecodeword after Polar encoding, to perform the rate matching. Theretransmission sequence after the matching is obtained, and then theretransmitted codeword for the (t−1)^(th) time is selected from theretransmission sequence after the matching.

In another optional implementation, when the preset rate matching mannerselects the puncturing rate matching, before obtaining the informationto be transmitted for the t^(th) time, the transmitting devicedetermines that the information to be transmitted for the t^(th) timemeets the preset condition. The preset condition herein includes one ormore of the following: a code length of the information to betransmitted for the t^(th) time belongs to a first preset range, a coderate of the information to be transmitted for the t^(th) time belongs toa second preset range, a quantity of the information bits in theextension locations in the information to be transmitted for the t^(th)time belongs to a third preset range, and a quantity of puncturing bitsin the foregoing codeword after the Polar encoding belongs to a fourthpreset range. The foregoing first transmission mode is selected when theforegoing preset condition is met.

The puncturing bits in the codeword after the Polar encoding may beunderstood as redundant bits in the codeword after the Polar encodingthat are determined based on the preset code length.

Threshold_4 is a threshold of the quantity of the puncturing bits.Optionally, Threshold_4=(¾)*N_(t-1), where N_(t-1) indicates a mothercode length during transmission for a (t−1)^(th) time (that is, lasttransmission). A mother code herein is a codeword after Polar encodingand before rate matching, that is, the foregoing codeword after thePolar encoding. In addition, the mother code length is an integral powerof 2, and is greater than or equal to a length of the information to betransmitted for the (t−1)^(th) time.

When a long code (the information to be transmitted for the t^(th) time)constructed during retransmission exceeds a limit of a system code rateand a code length, the CC HARQ mode is selected. For example, as aquantity of retransmission times increases, an overall code rate of asystem is less than Thredhold_1 or a code length of the information tobe transmitted for the t^(th) time is greater than Threshold_2. In thiscase, the system does not support the code length or code constructionat the code rate, and cannot perform the first transmission mode.Therefore, the CC HARQ mode is selected.

When the quantity of the information bits in the extension locations isrelatively small or a quantity of puncturing bits in the codeword afterthe Polar encoding is relatively large, the IR HARQ mode is selected.For example, when the quantity of information bits in the extensionlocations is smaller than Threshold_3 during retransmission, performancegain brought by introducing the information bits is less than or equalto performance loss brought by performing the check encoding on the newinformation bits. Therefore, in this case, it is selected not tointroduce the information bits, instead, the code length and the kernelare extended based on the information to be transmitted for the(t−1)^(th) time, and then extended bits are transmitted, that is, the IRHARQ mode is used for transmission. When a quantity of puncturing bitsin a codeword obtained after Polar encoding for a (t−1)^(th) time isgreater than Threshold_4, the IR HARQ mode is also selected fortransmission. This may bring a relatively large performance gain.

It can be learned that the first preset range is greater than or equalto Threshold_1, the second preset range is less than or equal toThreshold_2, the third preset range is greater than or equal toThreshold_3, and the fourth preset range is less than or equal toThreshold_4.

FIG. 4 is a schematic structural diagram of information to betransmitted for a t^(th) time according to an embodiment of thisdisclosure.

Optionally, based on the foregoing embodiment, before the transmittingdevice obtains the information to be transmitted for a t^(th) time, thetransmitting device determines whether reliability of K_(t) informationlocations in R extension locations is higher than reliability of K_(t)information locations with lowest reliability in information to betransmitted for a (t−1)^(th) time before the transmitting device obtainsthe information to be transmitted for a t^(th) time, where M_(t) isequal to K_(t)−L_(t).

To be specific, when constructing the information to be transmitted forthe t^(th) time, the transmitting device should determine whether thereliability of the K_(t) information locations in the R extensionlocations is higher than the reliability of the K_(t) informationlocations with lowest reliability in the information to be transmittedfor the (t−1)^(th) time. As shown in FIG. 4 , if there is thereliability of the K_(t) information locations in the R extensionlocations higher than the reliability of the K_(t) information locationswith lowest reliability in the information to be transmitted for the(t−1)^(th) time, the information bits with lowest reliability in theinformation to be transmitted for the (t−1)^(th) time are copied to theextension locations, and L_(t) check bits are obtained by check encodingand are also placed in the extension locations. The M_(t) informationbits may be the M_(t) information bits with lowest reliability in theinformation to be transmitted for the (t−1)^(th) time.

It should be noted that FIG. 4 is merely an example. During specificimplementation, reliability of locations in which the L_(t) check bitsare located may be higher than reliability of locations in which theinformation bits are located. The L_(t) check bits may alternatively becrossed with the M_(t) information bits, that is, one or moreinformation bits are adjacent to one or more check bits. This is notlimited to FIG. 4 .

Optionally, after the M_(t) information bits with lowest reliability inthe information to be transmitted for the (t−1)^(th) time are copied tothe extension locations, the original information locations with lowestreliability that is in the information to be transmitted for the(t−1)^(th) time and that are included in the information to betransmitted for the t^(th) time become frozen bits.

On the other hand, if reliability of the R extension locations is lowerthan reliability of the information locations (locations carryinginformation bits) in the information to be transmitted for the(t−1)^(th) time, the information bits are not copied to the extensionlocations, instead, Polar encoding is performed on the information to betransmitted for the (t−1)^(th) time, and information after the Polarencoding is sent to the receiving device. Correspondingly, afterobtaining a decoding result of a codeword for (t−1)^(th) retransmission,the receiving device may further determine whether the K_(t) informationlocations with highest reliability are in the decoding result of thecodeword for (t−1)^(th) retransmission, and if the information locationswith highest reliability exist in the decoding result of the codewordfor (t−1)^(th) retransmission, continue to perform check decoding on thedecoding result of the codeword for (t−1)^(th) retransmission.Otherwise, it is considered that the decoding result of the codeword for(t−1)^(th) retransmission is the known frozen bits.

It should be noted that the foregoing implementation is not limited. Insome scenarios, reliability of some bits in the extension locations islower than reliability of the K_(t) information locations with lowestreliability in the information to be transmitted for the (t−1)^(th)time, and the extension locations may alternatively be used to carryinformation.

In other words, it may be determined that the M_(t) informationlocations carry the M_(t) information bits in the extension locations,where M_(t) may not be equal to K_(t)−L_(t).

The foregoing M_(t) and L_(t) may be correlated. Optionally, theforegoing M_(t) and L_(t) may be positively correlated, that is, moreinformation bits in the extension locations indicate more check bitsrequired, so that a sufficient check capability is provided, and anexcessively higher probability of missing detection and incorrectdetection is avoided.

In a specific implementation process, L_(t) may alternatively bedetermined based on a specific requirement. For example, in theinformation to be transmitted for the t^(th) time, L_(t) mayalternatively be determined based on the following formula:

$L_{t} = \left\{ {\begin{matrix}{3,{5 < K_{t} \leq 10}} \\{4,{10 < K_{t} \leq {20}}} \\{5,{{20} < K_{t} \leq {50}}} \\{6,{{50} < K_{t} \leq 150}} \\{8,{K_{t} > 150}}\end{matrix}.} \right.$

Certainly, the foregoing examples are not used as a limitation. L_(t),M_(t), and K_(t) may all be preset fixed values. This is not limited inthis disclosure.

Optionally, in some scenarios, L_(t) may alternatively be 0.

FIG. 5 is a schematic structural diagram of a data retransmissionapparatus according to an embodiment of this disclosure. The apparatusmay be the foregoing transmitting device. As shown in FIG. 5 , theapparatus includes an obtaining module 501, an encoding module 502, adetermining module 503, and a transmitting module 504, where

the obtaining module 501 is configured to obtain information to betransmitted for a t^(th) time, where information to be transmitted for at^(th) time includes R_(t) extension locations and information to betransmitted for a (t−1)^(th) time, and the extension locations includeM_(t) information bits and L_(t) check bits corresponding to the M_(t)information bits, where R_(t), M_(t), and L_(t) are integers greaterthan 0, t is greater than 1, and M_(t) is less than R_(t);

the encoding module 502 is configured to perform polar encoding on theinformation to be transmitted for the t^(th) time, to obtain a codewordafter the Polar encoding;

the determining module 503 is configured to obtain a codeword for(t−1)^(th) retransmission based on the codeword after the Polarencoding; and

the transmitting module 504 is configured to transmit the codeword for(t−1)^(th) retransmission.

FIG. 6 is a schematic structural diagram of a data retransmissionapparatus according to still another embodiment of this disclosure. Asshown in FIG. 6 , based on FIG. 5 , the apparatus may further include anextension module 601, configured to: determine that reliability of K_(t)information locations in the R extension bits is higher than reliabilityof K_(t) information locations with lowest reliability in theinformation to be transmitted for the (t−1)^(th) time before theobtaining module 501 obtains the information to be transmitted for thet^(th) time, where M_(t) is equal to K_(t)−L_(t).

Optionally, M_(t) and L_(t) are positively correlated.

FIG. 7 is a schematic structural diagram of a data retransmissionapparatus according to still another embodiment of this disclosure. Asshown in FIG. 6 , based on FIG. 5 , the apparatus may further include adetermining module 701.

In an implementation, the determining module 701 is configured todetermine that the information to be transmitted for the t^(th) timemeets a preset condition before the obtaining module 501 obtains theinformation to be transmitted for the t^(th) time, where the presetcondition includes one or more of the following: a code length of theinformation to be transmitted for the t^(th) time belongs to a firstpreset range, a code rate of the information to be transmitted for thet^(th) time belongs to a second preset range, and a quantity of theinformation bits in the extension locations in the information to betransmitted for the t^(th) time belongs to a third preset range.

Optionally, in another implementation, the determining module 503 isspecifically configured to: perform rate matching on the codeword afterthe Polar encoding based on a preset code length and a preset ratematching manner, to obtain a to-be-retransmitted sequence after thematching, where the preset rate matching manner is one or more of thefollowing: puncturing rate matching, shortening rate matching, andrepetition rate matching; and obtain the codeword for (t−1)^(th)retransmission based on the to-be-retransmitted sequence after thematching.

When the preset rate matching manner is the puncturing rate matching,the determining module 701 is configured to determine that theinformation to be transmitted for the t^(th) time meets a presetcondition before the obtaining module obtains the information to betransmitted for the t^(th) time, where the preset condition includes oneor more of the following: a code length of the information to betransmitted for the t^(th) time belongs to a first preset range, a coderate of the information to be transmitted for the t^(th) time belongs toa second preset range, a quantity of the information bits in theextension locations in the information to be transmitted for the t^(th)time belongs to a third preset range, and a quantity of puncturing bitsin the codeword after the Polar encoding belongs to a fourth presetrange.

FIG. 8 is a schematic structural diagram of a data retransmissionapparatus according to still another embodiment of this disclosure. Theapparatus may be the foregoing receiving device. As shown in FIG. 8 ,the apparatus includes a receiving module 801 and a decoding module 802,where

the receiving module 801 is configured to receive a codeword for(t−1)^(th) retransmission sent by a transmitting device, where thecodeword for (t−1)^(th) retransmission is a retransmitted codewordobtained by the transmitting device based on a codeword after polarencoding that is obtained by information to be transmitted for a t^(th)time, the information to be transmitted for the t^(th) time includesR_(t) extension locations and information to be transmitted for a(t−1)^(th) time, and the extension locations include M_(t) informationbits and L_(t) check bits corresponding to the M_(t) information bits,where R_(t), M_(t), t, and L_(t) are integers greater than 0, t isgreater than 1, and M_(t) is less than R_(t); and

a decoding module 802 is configured to perform Polar decoding on thecodeword for (t−1)^(th) retransmission, to obtain a decoding result ofcodewords for t times of transmission.

Optionally, the decoding module 802 is specifically configured to:perform the Polar decoding on the codeword for (t−1)^(th)retransmission, to obtain a decoding result of the codeword for(t−1)^(th) retransmission; perform check decoding on the decoding resultof the codeword for (t−1)^(th) retransmission, to obtain a checkdecoding result; and determine a reliable decoding path based on thecheck decoding result, and decode, based on the reliable decoding path,codewords for first (t−1) times of transmission, to obtain the decodingresult of the codewords for t times of transmission.

For determining the reliable decoding path based on the check decodingresult, decoding, based on the reliable decoding path, the codeword for(t−1) times of transmission, and obtaining the decoding result of thecodewords for t times of transmission, the decoding module 802 isspecifically configured to: determine a decoding path with highestreliability based on the check decoding result, and delete anotherdecoding path other than the decoding path with the highest reliability;and decode, based on the decoding path with the highest reliability, thecodeword for first (t−1) times of transmission.

Further, the reliability of K_(t) information locations in the Rextension locations is higher than the reliability of K_(t) informationlocations with lowest reliability in the information to be transmittedfor the (t−1)^(th) time, where M_(t) is equal to K_(t)−L_(t).

Optionally, M_(t) and L_(t) are positively correlated.

Optionally, the information to be transmitted for the t^(th) time meetsa preset condition, where the preset condition includes one or more ofthe following: a code length of the information to be transmitted forthe t^(th) time belongs to a first preset range, a code rate of theinformation to be transmitted for the t^(th) time belongs to a secondpreset range, and a quantity of the information bits in the extensionlocations in the information to be transmitted for the t^(th) timebelongs to a third preset range.

Optionally, that the codeword for (t−1)^(th) retransmission is aretransmitted codeword obtained by the transmitting device based on acodeword after Polar encoding that is obtained by information to betransmitted for a t^(th) time includes: the codeword for (t−1)^(th)retransmission is obtained based on a to-be-retransmitted sequence thatis after matching and that is obtained by a codeword on which ratematching is performed in a preset rate matching manner and that isobtained by performing Polar encoding on the information to betransmitted for the t^(th) time, where the preset rate matching manneris one or more of the following: puncturing rate matching, shorteningrate matching, and repetition rate matching.

Correspondingly, when the preset rate matching manner is the puncturingrate matching, the information to be transmitted for the t^(th) timemeets a preset condition, where the preset condition includes one ormore of the following: a code length of the information to betransmitted for the t^(th) time belongs to a first preset range, a coderate of the information to be transmitted for the t^(th) time belongs toa second preset range, a quantity of the information bits in theextension locations in the information to be transmitted for the t^(th)time belongs to a third preset range, and a quantity of puncturing bitsin the codeword after the Polar encoding belongs to a fourth presetrange.

The foregoing apparatus may be configured to perform the methodsprovided in the foregoing method embodiments. Specific implementationsand technical effects are similar, and details are not described hereinagain.

It should be noted and understood that division into the modules of theforegoing apparatus is merely logical function division. During actualimplementation, some or all modules may be integrated into one physicalentity, or the modules may be physically separated. In addition, thesemodules may be all implemented in a form of software invoked by aprocessing element, or may be all implemented in a form of hardware; orsome modules may be implemented in a form of software invoked by aprocessing element, and some modules are implemented in a form ofhardware. For example, a determining module may be a processing elementseparately disposed, or may be integrated in a chip of the foregoingapparatus for implementation. In addition, the determining module may bestored in a memory of the foregoing apparatus in a form of program code,and is invoked by a processing element of the foregoing apparatus toperform a function of the foregoing determining module. Implementationsof other modules are similar thereto. In addition, all or some of themodules may be integrated together, or may be implemented separately.The processing element herein may be an integrated circuit and has asignal processing capability. In an implementation process, blocks inthe foregoing methods or the foregoing modules can be implemented byusing a hardware integrated logical circuit in the processing element,or by using instructions in a form of software.

For example, the foregoing modules may be configured as one or moreintegrated circuits implementing the foregoing methods, for example, oneor more application-specific integrated circuits (ASIC), one or moremicroprocessors (DSP), or one or more field programmable gate arrays(FPGA). For another example, when a module is implemented in a form ofprogram code invoked by a processing element, the processing element maybe a general-purpose processor, for example, a central processing unit(CPU) or another processor that can invoke the program code. For anotherexample, the modules may be integrated together, and implemented in aform of a system-on-a-chip (SOC).

FIG. 9 is a schematic structural diagram of a data retransmissionapparatus according to still another embodiment of this disclosure. Theapparatus may be integrated into the foregoing transmitting device. Asshown in FIG. 9 , the apparatus includes a memory 10 and a processor 11.

The memory 10 may be an independent physical unit, and may be connectedto the processor 11 by using a bus. Alternatively, the memory 10 and theprocessor 11 may be integrated together, and implemented by usinghardware, or the like.

The memory 10 is configured to store a program for implementing theforegoing methods embodiment or the modules in the embodiments shown inFIG. 5 to FIG. 7 . The processor 11 invokes the program to perform anoperation of the foregoing method embodiments.

FIG. 10 is a schematic structural diagram of a data retransmissionapparatus according to still another embodiment of this disclosure. Theapparatus may be integrated into the foregoing receiving device. Asshown in FIG. 10 , the apparatus includes a memory 20 and a processor21. The memory 20 may be an independent physical unit, and may beconnected to the processor 21 by using a bus. Alternatively, the memory20 and the processor 21 may be integrated together, and implemented byusing hardware or some software.

The memory 20 is configured to store a program for implementing theforegoing method embodiments or the modules in the embodiment shown inFIG. 8 . The processor 21 invokes the program to perform an operation ofthe foregoing method embodiments.

Optionally, when some or all of the data retransmission methods in theforegoing embodiments are implemented by using software, the dataretransmission apparatus may alternatively include only a processor. Thememory configured to store the program is located outside the dataretransmission apparatus. The processor is connected to the memory byusing a circuit/wire, and is configured to read and execute the programstored in the memory.

The processor may be a central processing unit (central processing unit,CPU), a network processor (network processor, NP), or a combination of aCPU and an NP.

The processor may further include a hardware chip. The foregoinghardware chip may be an application-specific integrated circuit (ASIC),a programmable logic device (PLD), or a combination thereof. Theforegoing PLD may be a complex programmable logic device (CPLD), afield-programmable logic gate array (FPGA), a generic array logic (GAL),or any combination thereof.

The memory may include a volatile memory, for example, a random accessmemory (RAM); or the memory may include a nonvolatile memory, forexample, a flash memory, a hard disk drive (HDD), or a solid-state drive(SSD); or the memory may include a combination of the foregoing types ofmemories.

FIG. 11 is a schematic interaction diagram of a communications systemaccording to an embodiment of this disclosure. As shown in FIG. 11 , thesystem includes a network device 101 and a terminal 102.

Referring to FIG. 11 , an encoding apparatus and a decoding apparatusmay be installed in the network device 101. Both the encoding apparatusand the decoding apparatus may be the foregoing data retransmissionapparatus. The data retransmission apparatus may alternatively be theencoding apparatus when serving as a transmitting device, and the dataretransmission apparatus may alternatively be the decoding apparatuswhen serving as a receiving device. In addition to the foregoingencoding apparatus and decoding apparatus, the network device 101 mayfurther include a transceiver 1102. A sequence obtained after encodingby the encoding apparatus may be sent to the terminal 102 by using thetransceiver 1102, or the transceiver 1102 is further configured toreceive information/data from the terminal 102. The information/data isconverted into a to-be-decoded sequence after a series of processing,and a decoding result is obtained after processing by the decodingapparatus.

As shown in FIG. 11 , the network device 101 may further include anetwork interface 1104, configured to communicate with another networkdevice.

Similarly, the foregoing encoding apparatus and the decoding apparatusmay be further installed in the terminal 102. In addition to theforegoing encoding apparatus and decoding apparatus, the terminal 102may further include a transceiver 1112. After being subsequently changedor processed, a sequence obtained after encoding by the encodingapparatus is sent to the network device 101 by using the transceiver1112, or the transceiver 1112 is further configured to receiveinformation/data from the network device 101. The information/data isconverted into a to-be-decoded sequence after a series of processing,and a decoding result is obtained after processing by the decodingapparatus. The terminal 102 may further include an input/outputinterface 1114, configured to receive information entered by a user.Information that should be sent to the network device 101 should beprocessed by the encoding apparatus and then sent to the network device101 by using the transceiver 1112. The decoding result obtained by thedecoding apparatus may alternatively be presented to the user by usingthe input/output interface 1114 after subsequent processing.

An embodiment of this disclosure further provides a computer storagemedium storing a computer program, and the computer program is used toperform the data retransmission methods provided in the foregoingembodiments.

An embodiment of this disclosure further provides a computer programproduct including an instruction, and when the instruction is run on acomputer, the computer is enabled to perform the data retransmissionmethods provided in the foregoing embodiments.

A person skilled in the art should understand that the embodiments ofthis disclosure may be provided as a method, a system, or a computerprogram product. Therefore, this disclosure may use a form of hardwareonly embodiments, software only embodiments, or embodiments with acombination of software and hardware. Moreover, this disclosure may usea form of a computer program product that is implemented on one or morecomputer-usable storage media (including but not limited to a diskmemory, a CD-ROM, an optical memory, and the like) that include computerusable program code.

This disclosure is described with reference to the flowcharts and/orblock diagrams of the methods, the device (system), and the computerprogram product according to the embodiments of this disclosure. Itshould be understood that computer program instructions may be used toimplement each process and/or each block in the flowcharts and/or theblock diagrams and a combination of a process and/or a block in theflowcharts and/or the block diagrams. These computer programinstructions may be provided for a general-purpose computer, aspecial-purpose computer, an embedded processor, or a processor of anyother programmable data processing device to generate a machine, so thatthe instructions executed by a computer or a processor of any otherprogrammable data processing device generate an apparatus forimplementing a specific function in one or more processes in theflowcharts and/or in one or more blocks in the block diagrams.

These computer program instructions may be stored in a computer readablememory that can instruct the computer or any other programmable dataprocessing device to work in a specific manner, so that the instructionsstored in the computer readable memory generate an artifact thatincludes an instruction apparatus. The instruction apparatus implementsa specific function in one or more processes in the flowcharts and/or inone or more blocks in the block diagrams.

These computer program instructions may be loaded onto a computer oranother programmable data processing device, so that a series ofoperations and blocks are performed on the computer or the anotherprogrammable device, thereby generating computer-implemented processing.Therefore, the instructions executed on the computer or the anotherprogrammable device provide methods, actions, operations, etc., forimplementing a specific function in one or more processes in theflowcharts and/or in one or more blocks in the block diagrams.

What is claimed is:
 1. A data retransmission method, comprising:obtaining, by a transmitting device, information to be transmitted for at^(th) time, wherein the information to be transmitted for the t^(th)time comprises R_(t) extension locations and information to beretransmitted for a (t−1)^(th) time, and the extension locationscomprise M_(t) information bits and L_(t) check bits corresponding tothe M_(t) information bits, wherein R_(t), M_(t), and L_(t) are integersgreater than 0, t is greater than 1, and M_(t) is less than R_(t);performing, by the transmitting device, polar encoding on theinformation to be transmitted for the t^(th) time, to obtain a codewordafter the polar encoding; obtaining, by the transmitting device, acodeword for (t−1)^(th) retransmission based on the codeword after thepolar encoding; and transmitting, by the transmitting device, thecodeword for (t−1)^(th) retransmission.
 2. The method of claim 1,wherein before the obtaining information to be transmitted for a t^(th)time, the method further comprises: determining, by the transmittingdevice, that reliability of K_(t) information locations in the R_(t)extension locations is higher than reliability of K_(t) informationlocations with lowest reliability in the information to be transmittedfor the (t−1)^(th) time, wherein M_(t) is equal to K_(t)−L_(t).
 3. Themethod of claim 2, wherein M_(t) and L_(t) are positively correlated. 4.The method of claim 1, wherein before the obtaining information to betransmitted for a t^(th) time, the method further comprises:determining, by the transmitting device, that the information to betransmitted for the t^(th) time meets a preset condition, wherein thepreset condition comprises one or more of: a code length of theinformation to be transmitted for the t^(th) time belongs to a firstpreset range, a code rate of the information to be transmitted for thet^(th) time belongs to a second preset range, or a quantity of theinformation bits in the extension locations in the information to betransmitted for the t^(th) time belongs to a third preset range.
 5. Themethod of claim 1, wherein the obtaining, by the transmitting device, acodeword for (t−1)^(th) retransmission based on the codeword after thepolar encoding comprises: performing, by the transmitting device, ratematching on the codeword after the polar encoding based on a preset codelength and a preset rate matching manner, to obtain ato-be-retransmitted sequence after the matching, wherein the preset ratematching manner comprises one or more of: puncturing rate matching,shortening rate matching, or repetition rate matching; and obtaining, bythe transmitting device, the codeword for (t−1)^(th) retransmissionbased on the to-be-retransmitted sequence after the matching.
 6. Themethod of claim 5, wherein when the preset rate matching mannercomprises puncturing rate matching, before the obtaining information tobe transmitted for a t^(th) time, the method further comprises:determining, by the transmitting device, that the information to betransmitted for the t^(th) time meets a preset condition, wherein thepreset condition comprises one or more of: a code length of theinformation to be transmitted for the t^(th) time belongs to a firstpreset range, a code rate of the information to be transmitted for thet^(th) time belongs to a second preset range, a quantity of theinformation bits in the extension locations in the information to betransmitted for the t^(th) time belongs to a third preset range, or aquantity of puncturing bits in the codeword after the polar encodingbelongs to a fourth preset range.
 7. A data retransmission method,comprising: receiving, by a receiving device, a codeword for (t−1)^(th)retransmission sent by a transmitting device, wherein the codeword for(t−1)^(th) retransmission is a retransmitted codeword obtained by thetransmitting device based on a codeword after polar encoding that isobtained by information to be transmitted for a t^(th) time, theinformation to be transmitted for the t^(th) time comprises R_(t)extension locations and information to be transmitted for a (t−1)^(th)time, and the extension locations comprise M_(t) information bits andL_(t) check bits corresponding to the M_(t) information bits, whereinR_(t), M_(t), and L_(t) are integers greater than 0, t is greater than1, and M_(t) is less than R_(t); and performing, by the receivingdevice, polar decoding on the codeword for (t−1)^(th) retransmission, toobtain a decoding result of codewords fort times of transmission.
 8. Themethod of claim 7, wherein the performing, by the receiving device,polar decoding on the codeword for (t−1)^(th) retransmission, to obtaina decoding result of codewords fort times of transmission comprises:performing, by the receiving device, the polar decoding on the codewordfor (t−1)^(th) retransmission, to obtain a decoding result of thecodeword for (t−1)^(th) retransmission; performing, by the receivingdevice, check decoding on the decoding result of the codeword for(t−1)^(th) retransmission, to obtain a check decoding result; anddetermining, by the receiving device, a reliable decoding path based onthe check decoding result, and decoding, based on the reliable decodingpath, codewords for first (t−1) times of transmission, to obtain thedecoding result of the codewords for the t times of transmission.
 9. Themethod of claim 8, wherein the determining, by the receiving device, areliable decoding path based on the check decoding result, and decoding,based on the reliable decoding path, codewords for first (t−1) times oftransmission comprises: determining, by the receiving device, a decodingpath with highest reliability based on the check decoding result, anddeleting a decoding path other than the decoding path with highestreliability; and decoding, based on the decoding path with highestreliability, the codeword for first (t−1) times of transmission.
 10. Themethod of claim 7, wherein reliability of K_(t) information locations inthe R extension locations is higher than reliability of K_(t)information bits with lowest reliability in the information to betransmitted for the (t−1)^(th) time, wherein M_(t) is equal toK_(t)−L_(t).
 11. The method of claim 10, wherein M_(t) and L_(t) arepositively correlated.
 12. The method of claim 7, wherein theinformation to be transmitted for the t^(th) time meets a presetcondition, and the preset condition comprises one or more of: a codelength of the information to be transmitted for the t^(th) time belongsto a first preset range, a code rate of the information to betransmitted for the t^(th) time belongs to a second preset range, or aquantity of the information bits in the extension locations in theinformation to be transmitted for the t^(th) time belongs to a thirdpreset range.
 13. The method of claim 7, wherein the codeword for(t−1)^(th) retransmission comprises a retransmitted codeword obtained bythe transmitting device based on a codeword after polar encoding that isobtained by information to be transmitted for a t^(th) time comprises:the codeword for (t−1)^(th) retransmission is obtained based on ato-be-retransmitted sequence that is after matching and that is obtainedby a codeword on which rate matching is performed in a preset ratematching manner and that is obtained by performing polar encoding on theinformation to be transmitted for the t^(th) time, wherein the presetrate matching manner is one or more of: puncturing rate matching,shortening rate matching, or repetition rate matching.
 14. The method ofclaim 13, wherein when the preset rate matching manner comprisespuncturing rate matching, the information to be transmitted for thet^(th) time meets a preset condition, and the preset condition comprisesone or more of: a code length of the information to be transmitted forthe t^(th) time belongs to a first preset range, a code rate of theinformation to be transmitted for the t^(th) time belongs to a secondpreset range, a quantity of the information bits in the extensionlocations in the information to be transmitted for the t^(th) timebelongs to a third preset range, or a quantity of puncturing bits in thecodeword after the polar encoding belongs to a fourth preset range. 15.A data retransmission apparatus, comprising: an obtaining module,configured to obtain information to be transmitted for a t^(th) time,wherein the information to be transmitted for the t^(th) time comprisesR_(t) extension locations and information to be retransmitted for a(t−1)^(th) time, and the extension locations comprise M_(t) informationbits and L_(t) check bits corresponding to the M_(t) information bits,wherein R_(t), M_(t), and L_(t) are integers greater than 0, t isgreater than 1, and M_(t) is less than R_(t); an encoding module,configured to perform polar encoding on the information to betransmitted for the t^(th) time, to obtain a codeword after the polarencoding; a determining module, configured to obtain a codeword for(t−1)^(th) retransmission based on the codeword after the polarencoding; and a transmitting module, configured to transmit the codewordfor (t−1)^(th) retransmission.
 16. The data retransmission apparatus ofclaim 15, wherein the apparatus further comprises: an extension module,configured to: determine that reliability of K_(t) information locationsin the R extension locations is higher than reliability of K_(t)information bits with lowest reliability in the information to betransmitted for the (t−1)^(th) time before the obtaining module obtainsthe information to be transmitted for the t^(th) time, wherein M_(t) isequal to K_(t)−L_(t).
 17. The data retransmission apparatus of claim 16,wherein M_(t) and L_(t) are positively correlated.
 18. The dataretransmission apparatus of claim 15, wherein the determining module isfurther configured to determine that the information to be transmittedfor the t^(th) time meets a preset condition before the obtaining moduleobtains the information to be transmitted for the t^(th) time, whereinthe preset condition comprises one or more of: a code length of theinformation to be transmitted for the t^(th) time belongs to a firstpreset range, a code rate of the information to be transmitted for thet^(th) time belongs to a second preset range, or a quantity of theinformation bits in the extension locations in the information to betransmitted for the t^(th) time belongs to a third preset range.
 19. Thedata retransmission apparatus of claim 15, wherein the determiningmodule is further configured to: perform rate matching on the codewordafter the polar encoding based on a preset code length and a preset ratematching manner, to obtain a to-be-retransmitted sequence after thematching, wherein the preset rate matching manner is one or more of:puncturing rate matching, shortening rate matching, or repetition ratematching; and obtain the codeword for (t−1)^(th) retransmission based onthe to-be-retransmitted sequence after the matching.
 20. The dataretransmission apparatus of claim 19, wherein when the preset ratematching manner comprises the puncturing rate matching, the determiningmodule is further configured to determine that the information to betransmitted for the t^(th) time meets a preset condition before theobtaining module obtains the information to be transmitted for thet^(th) time, wherein the preset condition comprises one or more of: acode length of the information to be transmitted for the t^(th) timebelongs to a first preset range, a code rate of the information to betransmitted for the t^(th) time belongs to a second preset range, aquantity of the information bits in the extension locations in theinformation to be transmitted for the t^(th) time belongs to a thirdpreset range, or a quantity of puncturing bits in the codeword after thepolar encoding belongs to a fourth preset range.